Targeting the GBCA Ligand: A Study of Gadolinium Toxicity in the Intracellular Vesicle Transport System

Abstract

Gadolinium-Based Contrast Agents (GBCAs) are medical dyes used to improve diagnostic accuracy of MRI images. Gadolinium is a metal toxic to cells when unchelated. Therefore, GBCA manufacturers bind it to a ligand so it can move safely through the extracellular matrix. Research demonstrates that gadolinium can dechelate from its ligand– particularly when exposed to weak Lewis acids– and enter cells, contributing to cytotoxic effects. We sought to mimic in vivo conditions that dechelate gadolinium and examine the resulting effects on the vesicle transport system. We applied a combination of GBCAs, oxalic acid (a weak Lewis acid), and ascorbic acid (an oxalic acid precursor) to HEK293 kidney and T98G glioblastoma cells. Three rounds of experiments were conducted. In the first, both cell lines were exposed to all treatment combinations for 48 hours, lysed, and analyzed using western blot. The second round mimicked the first, but cell pellets and media were harvested for MP-AES analysis. In the third, HEK-293 cells were exposed to all treatment combinations for 72 hours before immunocytochemistry (ICC) was performed. ICC analysis shows that the oxalic acid+ascorbic acid+GBCA and oxalic acid+GBCA treatments increase LAMP2 protein. Ongoing research aims to investigate whether gadolinium dechelation occurred, along with other altered proteomic interactions within the vesicle transport system, providing insight into the mechanisms of intracellular toxicity.